7a901108c4
This is a bundle of disparate changes that enable testing the creating of a guest instance. At a high level these are: * Add helpers for downloading ubuntu images. * Add method for setting up a basic overcloud network. This is very similar to zaza.configure.network.run_from_cli * Add nova setup module that includes create_flavors and manage_ssh_key * Add nova test base class for launching an instance and two derived classes for launching a cirros and lts image respectively. * Fixes to zaza.charm_tests.test_utils after the refactor of the model argument in zaza.models * New certs.is_keys_valid function to check if a public and private key are a pair. * Methods in utilities.openstack for managing ssh keys. On creation of a new key the private key is stored locally and the public key is retrieved from Openstack * Methods in utilities.openstack for testing guests at various points of the creation process.